Previous versions supported the Oracle Solaris operating system and SPARC architecture.
Oracle's primary implementation of the JVMS is known as the HotSpot (virtual machine).
The JDK also comes with a complete Java Runtime Environment (JRE), usually called a private runtime, due to the fact that it is separated from the "regular" JRE and has extra contents.
Copies of the JDK also include a wide selection of example programs demonstrating the use of almost all portions of the Java API.
All adhere to the basic Java specifications, but often differ in explicitly unspecified areas, such as garbage collection, compilation strategies, and optimization techniques.